Early marker of proteinuria in patients treated with an anti-VEGF treatment

ABSTRACT

This document provides methods and materials related to determining whether or not a human receiving a therapy (e.g., an anti-VEGF therapy such as a bevacizumab therapy) has developed or is at risk for developing proteinuria. For example, methods and materials for detecting urinary podocytes to determine whether or not a human receiving anti-VEGF therapy has or is at risk for developing proteinuria or kidney injury are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 13/518,358, filed Jun. 21, 2012, which is a National Stage application under 35 U.S.C. 371 and claims benefit of International Application No. PCT/US2010/061543 having an International Filing Date of Dec. 21, 2010, which claims the benefit of U.S. Provisional Application Ser. No. 61/288,514, filed Dec. 21, 2009. The disclosures of the prior applications are considered part of (and are incorporated by reference in) the disclosure of this application.

BACKGROUND

1. Technical Field

This document relates to methods and materials involved in determining whether or not a human receiving an anti-VEGF therapy has podocyturia (e.g., urinary excretion of podocytes). For example, this document provides methods and materials for detecting the presence or absence of podocytes in a urine sample from a human receiving an anti-VEGF therapy to determine whether or not the human has developed or is at risk for developing proteinuria or kidney injury.

2. Background Information

Angiogenesis has a critical role in the growth, invasion, and metastasis of malignancies. Using angiogenesis inhibitors as an approach to cancer treatment has made significant progress in the field of cancer therapy. Agents that target the vascular endothelial growth factor (VEGF) signaling pathway are advancing in clinical development. However, a side effect in about 30% of cancer patients receiving anti-VEGF therapy is proteinuria (≧300 mg of total protein in a 24-hour urine sample). Proteinuria can be associated with characteristic renal pathologic changes of glomerular endotheliosis, leading to renal toxicity. One example of an anti-VEGF therapy is bevacizumab (Avastin®), a humanized recombinant monoclonal antibody directed against VEGF.

SUMMARY

This document provides methods and materials related to determining whether or not a human receiving an anti-VEGF therapy (e.g., bevacizumab) has developed or is at risk for developing proteinuria. For example, this document provides methods and materials for detecting urinary podocytes to determine whether or not a human receiving anti-VEGF therapy has or is at risk for developing proteinuria or kidney injury as indicated by podocyturia. Identifying patients who have podocyturia can allow such patients, who have or are at risk for developing toxicity as a result of the clinical use of drugs, to be treated effectively. In addition, identifying patients who do not have podocyturia can avoid unnecessary cessation of anti-VEGF therapy. As described herein, the presence of urinary podocytes can be used to identify humans receiving anti-VEGF therapy as having proteinuria or as being at risk for developing proteinuria as indicated by podocyturia.

In general, one aspect of this document features a method for assessing a human receiving an anti-VEGF therapy for a risk of developing proteinuria or renal injury. The method comprises, or consists essentially of, determining whether or not a urine sample from a human receiving anti-VEGF therapy contains urinary podocytes or evidence of urinary podocytes (e.g., podocyte remnants), wherein the presence of such podocytes indicates that the human is at risk for developing proteinuria.

In another aspect, this document features a method for assessing a human receiving an anti-VEGF therapy for proteinuria. The method comprises, or consists essentially of, determining whether or not a urine sample from a human receiving anti-VEGF therapy contains urinary podocytes or evidence of urinary podocytes (e.g., podocyte remnants), wherein the presence of such podocytes indicates that the human has proteinuria.

In another embodiment, this document describes a method for assessing a human receiving an anti-VEGF therapy for proteinuria, wherein the detection of proteinuria demonstrates renal injury.

The anti-VEGF therapy can be a bevacizumab therapy, a sunitinib therapy, a sorafenib therapy, or other known or effective therapies. The therapy may be a monoclonal or poloyclonal antibody therapy.

In another aspect, a human receiving an anti-epidermal growth factor receptor (EGFR) therapy, instead of or in addition to an anti-VEGF therapy, can be assessed for proteinuria or the risk of developing proteinuria or kidney injury as described herein with respect to an anti-VEGF therapy.

In some cases, podocytes can be detected in, for example, a urine sample using an antibody against a protein expressed by podocytes, such as podocin. In some cases, the antibody can be an antibody directed against a podocalyxin polypeptide, a nephrin polypeptide, or a synaptopodin polypeptide. Podocytes, or their fragments, can be detected using any appropriate method including, without limitation, cell staining techniques, immunocytochemistry techniques, and flow cytometry using, for example, anti-podocin antibodies.

In another aspect, this document features a method for assessing a human who has received an anti-VEGF therapy for a risk of developing proteinuria. The method comprises, or consists essentially of, determining whether or not a urine sample from a human receiving anti-VEGF therapy contains one or more urinary podocytes or evidence of one or more urinary podocytes, wherein the presence of the one or more urinary podocytes or the evidence indicates that the human is at risk for developing proteinuria. The anti-VEGF therapy can be selected from the group consisting of a bevacizumab therapy, a sunitinib therapy, and a sorafenib therapy. The determining step can comprise using an antibody to detect podocytes. The determining step can comprise using flow cytometry to detect podocytes. The antibody can be an anti-podocin antibody. The method can comprise detecting the presence of the one or more urinary podocytes. The method can comprise classifying the mammal as being at risk of developing proteinuria based at least in part on the presence of the one or more urinary podocytes. The method can comprise detecting the absence of the one or more urinary podocytes. The method can comprise classifying the mammal as not being at risk of developing proteinuria based at least in part on the absence of the one or more urinary podocytes. The human can be a non-pregnant human. The method can comprise determining whether or not the urine sample contains a level of urinary podocytes greater than about three or more urinary podocytes (e.g., greater than 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more urinary podocytes) per high power microscope field (400×).

In another aspect, this document features a method for assessing a human who has received an anti-VEGF or anti-EGFR therapy for proteinuria or a risk of developing proteinuria. The method comprises, or consists essentially of, determining whether or not a urine sample from a human receiving anti-VEGF therapy or an anti-EGFR therapy contains one or more urinary podocytes or evidence of one or more urinary podocytes, classifying the human as having or as being at risk of developing proteinuria if the one or more urinary podocytes or the evidence are present in the urine sample, and classifying the human as not having or as not being at risk of developing proteinuria if the one or more urinary podocytes and the evidence are not present in the urine sample. The human can be a human who received the anti-VEGF therapy. The anti-VEGF therapy can be selected from the group consisting of a bevacizumab therapy, a sunitinib therapy, and a sorafenib therapy. The determining step can comprise using an antibody to detect podocytes. The antibody can be an anti-podocin antibody. The determining step can comprise using flow cytometry to detect podocytes. The method can comprise detecting the presence of the one or more urinary podocytes. The method can comprise detecting the absence of the one or more urinary podocytes. The human can be a non-pregnant human. The method can comprise determining whether or not the urine sample contains a level of urinary podocytes greater than about three or more urinary podocytes (e.g., greater than 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more urinary podocytes) per high power microscope field (400×).

In another aspect, this document features a method for identifying a human who has received an anti-VEGF or anti-EGFR therapy as having proteinuria or a risk of developing proteinuria. The method comprises, or consists essentially of, detecting the presence of one or more podocytes in a urine sample of a human who received anti-VEGF therapy or an anti-EGFR therapy, and classifying the human as having or as being at risk of developing proteinuria based at least in part on the presence. The human can be a human who received the anti-VEGF therapy. The anti-VEGF therapy can be selected from the group consisting of a bevacizumab therapy, a sunitinib therapy, and a sorafenib therapy. The detecting step can comprise using an antibody to detect the one or more podocytes. The antibody can be an anti-podocin antibody. The detecting step can comprise using flow cytometry to detect the one or more podocytes. The human can be a non-pregnant human. The presence of the one or more podocytes in the urine sample can be detected by detecting the presence of remnants of one or more urinary podocytes. The method can comprise determining whether or not the urine sample contains a level of urinary podocytes greater than about three or more urinary podocytes (e.g., greater than 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more urinary podocytes) per high power microscope field (400×).

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar or equivalent to those described herein can be used to practice the invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 contains a photograph of urinary cells plated on a collagen-coated slide, cultured for 24 hours, and stained for podocin immunoreactivity.

DETAILED DESCRIPTION

This document provides methods and materials for determining whether or not a human who received or is receiving an anti-VEGF therapy has developed or is at risk for developing proteinuria as indicated by podocyturia. For example, this document provides methods and materials for determining whether or not a human (e.g., a non-pregnant cancer patient) treated with an anti-VEGF therapy has an elevated level of urinary podocytes, thereby indicating that the human has developed or is at risk for developing proteinuria. As disclosed herein, the detection of one or more podocytes or evidence of podocytes (e.g., podocyte remnants) in the urine of a human is indicative that the human developed or is at risk of developing proteinuria. The presence of proteinuria may indicate that the human is experiencing or at risk of developing renal injury. Severe proteinuria may be indicative of nephrotic syndrome.

The methods and materials provided herein can be used to assess any type of human who received or is receiving an anti-VEGF therapy, an anti-EGFR therapy, or a combination of an anti-VEGF therapy and an anti-EGFR therapy. For example, the methods and materials provided herein can be used to assess male or female humans for proteinuria or a risk of developing proteinuria. In some cases, the methods and materials provided herein can be used to assess non-pregnant humans who received or are receiving an anti-VEGF therapy, an anti-EGFR therapy, or a combination of an anti-VEGF therapy and an anti-EGFR therapy for proteinuria or a risk of developing proteinuria. Examples of anti-VEGF therapies include, without limitation, bevacizumab therapies, sunitinib therapies, and sorafenib therapies. Examples of anti-EGFR therapies include, without limitation, cetuximab therapies, panitumumab therapies, trastuzumab therapies, lapatinib therapies, erlotinib therapies, and geftinib therapies.

Any appropriate method can be used to determine the level of podocytes in a human's urine. For example, cell staining techniques that include using antibodies that bind to podocytes or polypeptides expressed by podocytes can be used. Examples of such antibodies include, without limitation, antibodies that have the ability to bind a podocin polypeptide (e.g., GenBank GI No. 7657615; Accession No. NP_(—)055440.1), a podocalyxin polypeptide (e.g., GenBank GI No. 66277202, Accession No. NP_(—)001018121.1; GenBank GI No. 33598950, Accession No. NP_(—)005388.2; GenBank GI No. 7271815, Accession No. AAB61574.1; and GenBank GI No. 7657465, Accession No. NP_(—)056535.1), a nephrin polypeptide (e.g., GenBank GI No. 10441644; Accession No. AAG17141.1), a synaptopodin polypeptide (e.g., GenBank GI No. 33323347; Accession No. AAQ07403.1), a Neph1 polypeptide (e.g., GenBank GI No. 14572521; Accession No. AAK00529.1), a GLEPP1 polypeptide (e.g., GenBank GI No. 885926; Accession No. AAA82892.1), a WT1 polypeptide (e.g., GenBank GI No. AAH46461.2; Accession No. 110611793), a CD2AP polypeptide (e.g., GenBank GI No. 11321634; Accession No. NP_(—)036252.1), an actin polypeptide (e.g., GenBank GI No. 4501881; Accession No. NP_(—)001091.1), an actinin polypeptide (e.g., GenBank GI No. 3157976; Accession No. AAC17470.1), a cadherin polypeptide (e.g., GenBank GI No. 2281027; Accession No. BAA21569.1), a catenin polypeptide (e.g., GenBank GI No. 4503131; Accession No. NP_(—)001895.1), an integrin polypeptide (e.g., GenBank GI No. 47078292; Accession No. NP_(—)000203.2), a vinculin polypeptide (e.g., GenBank GI No. 340237; Accession No. AAA61283.1), a talin polypeptide (e.g., GenBank GI No. 6682361; Accession No. AAF23322.1), a paxillin polypeptide (e.g., GenBank GI No. 704348; Accession No. AAC50104.1), or a ZO-1 polypeptide (e.g., GenBank GI No. 116875767; Accession No. NP_(—)003248.3). In some cases, flow cytometry techniques can be used to determine the level of podocytes present in a human urine sample. The podocytes detected in a urine sample can be viable podocytes, non-viable podocytes, or a combination thereof. In some cases, non-viable podocytes can be identifiable podocyte remnants.

An antibody can be, without limitation, a polyclonal, monoclonal, human, humanized, chimeric, or single-chain antibody, or an antibody fragment having binding activity, such as a Fab fragment, F(ab′) fragment, Fd fragment, fragment produced by a Fab expression library, fragment comprising a VL or VH domain, or epitope binding fragment of any of the above. An antibody can be of any type (e.g., IgG, IgM, IgD, IgA or IgY), class (e.g., IgG1, IgG4, or IgA2), or subclass. In addition, an antibody can be from any animal including, without limitation, birds and mammals. For example, an antibody can be a human, rabbit, sheep, or goat antibody. An antibody can be naturally occurring, recombinant, or synthetic. Antibodies can be generated and purified using any appropriate method. For example, monoclonal antibodies can be prepared using hybridoma, recombinant, or phage display technologies, or a combination of such technologies. In some cases, antibody fragments can be produced synthetically or recombinantly from a gene encoding a partial antibody sequence. Any antibody that can be used to detect podocytes (e.g., anti-podocin antibodies, anti-podocalyxin antibodies, anti-nephrin antibodies, or anti-synaptopodin antibodies) can have a binding affinity for its antigen of at least 10⁴ mol⁻¹(e.g., at least 10¹, 10⁶, 10⁷, 10⁸, 10⁹, 10¹⁰, 10¹¹, or 10¹² mol⁻¹). For example, an anti-podocin antibody that binds to podocin polypeptides at an affinity of at least 10⁴ mol⁻¹(e.g., at least 10¹, 10⁶, 10⁷, 10⁸, 10⁹, 10¹⁰, 10¹¹, or 10¹² mol⁻¹) can be used as described herein.

The term “elevated level” as used herein with respect to the level of urinary podocytes is any level that is above a median level of podocytes present in urine from a random population of non-pregnant humans known not to have proteinuria (e.g., a random population of 5, 10, 15, 20, 30, 40, 50, 100, 500, or more non-pregnant humans known not to have proteinuria). For example, the random population of non-pregnant humans can be a population of non-pregnant humans receiving an anti-VEGF therapy or a population of non-pregnant humans not receiving an anti-VEGF therapy, provided that the humans do not have proteinuria. In some cases, the random population of non-pregnant humans can be a population of non-pregnant humans receiving an anti-EGFR therapy or a population of non-pregnant humans not receiving an anti-EGFR therapy, provided that the humans do not have proteinuria. In some cases, an elevated level of urinary podocytes can be a detectable level of podocytes (e.g., podocin-positive cells) within a urine sample. The presence or absence of such a detectable level of podocytes (e.g., podocin-positive cells) can be determined using an anti-podocin antibody.

Once the level of urinary podocytes of a human is determined, then the level can assessed to determine if the level is an elevated level. The presence of an elevated level of urinary podocytes can indicate that the human has proteinuria or a risk of developing proteinuria. Additional clinical tests can be performed to confirm that a human having an elevated level of urinary podocytes has proteinuria. For example, a total protein determination in a 24-hour urine collection test, a urine dipstick protein analysis test, and/or a protein-creatinine ratio test in a random urine sample can be performed to confirm that a human having an elevated level of urinary podocytes has proteinuria. If the presence of proteinuria is confirmed by an additional clinical test (e.g., a total protein determination in a 24-hour urine collection test) for a human having an elevated level of urinary podocytes, then that human can be classified as having proteinuria. If the presence of proteinuria is not confirmed by an additional clinical test (e.g., a total protein determination in a 24-hour urine collection test) for a human having an elevated level of urinary podocytes, then that human can be classified as being at risk of developing proteinuria.

In some cases, the level of urinary podocytes present within a human can be assessed using a cutoff value such as 0.85 urinary podocytes present per mg creatinine. For example, once the level of urinary podocytes of a human is determined, the level can compared to a cutoff value (e.g., 0.85 urinary podocytes/mg creatinine) The presence of a level of urinary podocytes greater than or equal to the cutoff value can indicate that the human has proteinuria or a risk of developing proteinuria. Additional clinical tests can be performed to confirm that a human having a level of urinary podocytes greater than or equal to the cutoff value has proteinuria. For example, a total protein determination in a 24-hour urine collection test, a urine dipstick protein analysis test, and/or a protein-creatinine ratio test in a random urine sample can be performed to confirm that a human having a level of urinary podocytes greater than or equal to the cutoff value has proteinuria. If the presence of proteinuria is confirmed by an additional clinical test (e.g., a total protein determination in a 24-hour urine collection test) for a human having a level of urinary podocytes greater than or equal to the cutoff value, then that human can be classified as having proteinuria. If the presence of proteinuria is not confirmed by an additional clinical test (e.g., a total protein determination in a 24-hour urine collection test) for a human having a level of urinary podocytes greater than or equal to the cutoff value, then that human can be classified as being at risk of developing proteinuria.

In some cases, a human treated with an anti-VEGF therapy, an anti-EGFR therapy, or both can be classified as having proteinuria or a risk of developing proteinuria if it is determined that the podocyte level in a urine sample from the human treated with the therapy (e.g., the anti-VEGF therapy, anti-EGFR therapy, or both) is greater than the podocyte level in a urine sample obtained from that human at an earlier time point (e.g., at a time prior to any treatments with an anti-VEGF therapy or an anti-EGFR therapy). Additional clinical tests can be performed to confirm that a human experiencing such an increase in urinary podocytes over time has proteinuria. For example, a total protein determination in a 24-hour urine collection test, a urine dipstick protein analysis test, and/or a protein-creatinine ratio test in a random urine sample can be performed to confirm that a human experiencing an increase in urinary podocytes over time has proteinuria. If the presence of proteinuria is confirmed by an additional clinical test (e.g., a total protein determination in a 24-hour urine collection test) for a human experiencing an increase in urinary podocytes over time, then that human can be classified as having proteinuria. If the presence of proteinuria is not confirmed by an additional clinical test (e.g., a total protein determination in a 24-hour urine collection test) for a human experiencing an increase in urinary podocytes over time, then that human can be classified as being at risk of developing proteinuria.

In some cases, the detection of one or more podocytes in a urine sample can be indicative of podocyturia. For example, a non-pregnant patient receiving an anti-VEGF therapy or anti-EGFR therapy (or both) can be classified as having proteinuria or a risk of developing proteinuria based at least in part on the detection of one or more podocytes in a urine sample. Additional clinical tests can be performed to confirm that a human having one or more detectable urinary podocytes has proteinuria. For example, a total protein determination in a 24-hour urine collection test, a urine dipstick protein analysis test, and/or a protein-creatinine ratio test in a random urine sample can be performed to confirm that a human having one or more detectable urinary podocytes has proteinuria. If the presence of proteinuria is confirmed by an additional clinical test (e.g., a total protein determination in a 24-hour urine collection test) for a human having one or more detectable urinary podocytes, then that human can be classified as having proteinuria. If the presence of proteinuria is not confirmed by an additional clinical test (e.g., a total protein determination in a 24-hour urine collection test) for a human having one or more detectable urinary podocytes, then that human can be classified as being at risk of developing proteinuria.

A human treated with an anti-VEGF therapy, an anti-EGFR therapy, or both can be monitored using the methods and materials provided herein. Podocytes may appear in a patient's urine before any proteinuria is detected, thus providing an early predictor of a pending adverse event. This early indication may allow health care personnel to alter a patient's anti-VEGF or anti-EGFR treatment plan or to begin treatment for proteinuria. For example, the level of podocytes in a urine sample can be assessed to determine whether or not proteinuria persists in response to decreasing the dose of anti-VEGF therapy or anti-EGFR therapy.

This document also provides methods and materials to assist medical or research professionals in determining whether or not a human treated with an anti-VEGF therapy, an anti-EGFR therapy, or both has or is developing proteinuria. Medical professionals can be, for example, doctors, nurses, medical laboratory technologists, and pharmacists. Research professionals can be, for example, principal investigators, research technicians, postdoctoral trainees, and graduate students. A professional can be assisted by (1) determining the level of urinary podocytes in a urine sample, and (2) communicating information about the level to that professional. In some cases, a professional can be assisted by (1) assessing a urine sample of the presence of urinary podocytes, and (2) communicating information about the presence of urinary podocytes to that professional.

Any appropriate method can be used to communicate information to another person (e.g., a professional). For example, information can be given directly or indirectly to a professional. In addition, any type of communication can be used to communicate the information. For example, mail, e-mail, telephone, and face-to-face interactions can be used. The information also can be communicated to a professional by making that information electronically available to the professional. For example, the information can be communicated to a professional by placing the information on a computer database such that the professional can access the information. In addition, the information can be communicated to a hospital, clinic, or research facility serving as an agent for the professional.

This document also provides methods and materials for treating humans with an anti-VEGF therapy such as bevacizumab, an anti-EFGR therapy, or both under conditions that reduce the likelihood of inducing proteinuria. For example, a human needing an anti-VEGF therapy (e.g., a human cancer patient needing bevacizumab treatment) can be administered a standard dose of bevacizumab (e.g., 5-15 mg/kg/day) for a limited number of dosing cycles administered once every week, every two weeks, or every three weeks. At least once within the first 3 days of treatment, a urine sample can be obtained and assessed for urinary podocytes as described herein. If urinary podocytes are detected or an elevated level of urinary podocytes is detected, then the dose of the anti-VEGF therapy can be reduced by at least 30 percent (e.g., 30, 40, 50, 75, 80, 90, or 100 percent) for a period of time. Alternatively, anti-VEGF therapy can be skipped for one or two dosing cycles for a period of time so medication is received every four weeks or every six weeks. After this period of time, a urine sample can be obtained and assessed for urinary podocytes as described herein. If urinary podocytes are not detected or an elevated level of urinary podocytes is not detected, then the dose of the anti-VEGF therapy can be increased (e.g., increased to the original dose or to some degree less than the original dose). If urinary podocytes are detected or an elevated level of urinary podocytes is detected, then the dose or the frequency of the anti-VEGF therapy can be reduced further for an additional period of time (e.g., once every week, every two weeks, every three weeks, or more cycles). The assessment of urine for urinary podocytes or urinary podocyte levels and the adjustment of anti-VEGF therapy dosage can be repeated multiple times until a dose of anti-VEGF therapy is reached that does not induce proteinuria as determined by the presence or level of urinary podocytes detected.

It is noted that while the methods and materials described are understood for patients receiving anti-VEGF therapy, anti-EGFR therapy, or both, patients receiving other therapies, such as non-steroidal anti-inflamatory drugs, bisphosphonate, trastuzumab, capecitabine, paclitaxel, or anthracycline therapy may also be assessed for having proteinuria or being at risk for developing proteinuria as indicated by podocyturia.

The invention will be further described in the following examples, which do not limit the scope of the invention described in the claims.

EXAMPLES Example 1 A Case of Podocyturia in a Patient Receiving Anti-VEGF Therapy with Sunitinib

Case Study

A 67 year old female presented with a 7.2×6.1 cm mass involving the central and lower portion of the right kidney. Renal function was normal with a creatinine of 1.0 and no proteinuria. She subsequently underwent a right radical nephrectomy and retroperitoneal lymphadenectomy. Pathology confirmed Grade 2, T2, N0, M1 renal cell carcinoma, clear cell type. Sunitinib therapy was initiated, with good response.

Four months into therapy, renal function worsened with a peak creatinine of 1.5 and 467 mg of protein in 24 hours. Angiotensin receptor blockade with Diovan was initiated. Additional side effects included hypertension, hand and foot syndrome, and drug-induced hypothyroidism.

After seven months of therapy, her creatinine improved to 1.3 but she remained proteinuric, with a predicted 24 hour protein of 931 mg. At that time, a podocyturia assay was performed as described below and the presence of urinary podocytes was confirmed (FIG. 1).

Detection of Podocytes

A random urine sample (25-50 mL each) was centrifuged for 8 minutes at 700 g at room temperature. The pellets were rinsed twice with human diploid fibroblast (HDF) solution. Next, the pellets were resuspended in Dulbecco's modified eagle's medium (DMEM) F-12 medium with 10% fetal bovine serum that was supplemented with antibiotics for the prevention of bacterial contamination. A one-milliliter aliquot was plated on a collagen-coated tissue culture slide, which was followed by overnight incubation at 37° C. in 5% CO₂. The next day, the media were removed, followed by two phosphate-buffered saline solution washes. The slide was fixed with 1 mL of ice cold methanol for 10 minutes at −20° C. The slide was incubated with antibodies to podocin (dilution, 1:200). After being washed with phosphate-buffered saline solution, a secondary fluorescein isothiocyanate-labeled antibody was added at a dilution of 1:40 for 30 minutes. The sediment was counterstained with Hoechst nuclear stain to facilitate differentiation of whole cells from cell fragments. Coverslips were mounted with Vectashield (Vector Labs, Burlington, Calif.), and the slides were viewed with a fluorescence microscope (Leica, Germany). Nucleated, positive-staining cells were considered to be podocytes. A renal pathologist, who was blinded to the clinical diagnosis and laboratory findings, evaluated each sample to determine the number of cells that were present and the percentage of cells that were stained for podocin.

For the patient presented, the regimen of Sunitinib was changed, and the dose was decreased. Her kidney function, as per creatinine measurements, improved. She remains proteinuric, but her kidney function remains stable.

A test is positive for proteinuria if the number of podocytes expressed as a ratio to the creatinine content of the respective urine sample is greater than 0.85 podocytes/mg creatinine.

The results provided herein indicated that an elevated level of urinary podocytes is a marker of proteinuria in humans being treated with an anti-VEGF therapy. In controls, two patients on anti-VEGF therapy without proteinuria, podocyturia was not observed.

Example 2 Podocyturia in Patients Treated with VEGF Blocking Therapy for Cancer

The following was performed to determine whether podocyturia is present in patients who, while undergoing anti-VEGF therapy, develop proteinuria (Table 1). In addition, urinary podocyte excretion was compared among patients on anti-VEGF therapy with proteinuria ranging from 101 to 9720 mg/d (Table 1).

TABLE 1 Anti- Type of Cancer Age/Sex VEGF GFR Proteinuria Cells/HPF Cholangio 68/F B 66  420 mg/d 0 Renal Cell 60/M S/nib 39  101 mg/d 1 Colorectal 55/F B 137 1 + dipstick 1 Colon 66/F B + S/nib 77  330 mg/d 0 GBM 59/F B + S/nib 78  152 mg/d 1 Renal Cell 73/M B 63 2144 mg/d >3 Renal Cell 67/F Sunitib 43 2112 mg/d >3 SBC 68/M B 59 6361 mg/d >3 GBM 70/M S/nib 70 9720 mg/d >9 GBM: glioblastoma multiforme; SBC: small bowel carcinoid; B: bevacizumab; S/nib: sorafenib; HPF: 400x high power field.

These results demonstrate a higher degree of podocyturia in patients undergoing anti-VEGF therapy with proteinuria in excess of 2 gr/d compared to those treated with the same agents and proteinuria <0.5 gr/d.

OTHER EMBODIMENTS

It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims. 

What is claimed is:
 1. A method for using an anti-VEGF therapy, without inducing proteinuria, to treat cancer in a human having cancer, wherein said method comprises: (a) administering an initial dose of said anti-VEGF therapy to said human to treat said cancer, (b) obtaining a urine sample from said human receiving said anti-VEGF therapy, (c) contacting said urine sample with an antibody that binds to podocytes or polypeptides expressed by podocytes to form an antigen-antibody complex, if podoycytes or polypeptides expressed by podocytes are present in said sample, (d) detecting, by flow cytometry, the presence of said antigen-antibody complex, thereby identifying said human as being at risk of developing proteinuria, if said complex is detected and (e) administering a subsequent dose of said anti-VEGF therapy to said human who does not have proteinuria, but in whom the antigen-antibody complex has been detected, wherein said subsequent dose is at least 30 percent lower than said initial dose.
 2. The method of claim 1, wherein said method is a method for treating a human with said anti-VEGF therapy, wherein said method comprises administering an initial dose of said anti-VEGF therapy, and wherein said method comprises administering a subsequent dose of said anti-VEGF therapy.
 3. The method of claim 2, wherein said anti-VEGF therapy is selected from the group consisting of a bevacizumab therapy, a sunitinib therapy, and a sorafenib therapy.
 4. The method of claim 1, wherein said human is a non-pregnant human.
 5. The method of claim 1, wherein said administering said initial dose comprises administering between 5 and 15 mg of said anti-VEGF therapy per kg of body weight of said human per day once every week, once every two weeks, or once every three weeks.
 6. The method of claim 1, wherein said urine sample is obtained from said human within at least three days of administration of said initial dose.
 7. The method of claim 1, wherein said antibody is an anti-podocin antibody. 